My copending application Ser. No. 546,548 filed on FEB. 3, 1975 and entitled "Flow Control Valve" discloses a drip irrigation valve which allows the flow rate through the valve to be manually selected and which has pressure compensating features. As used herein, pressure compensating means an ability to increase the restriction to flow in response to inlet pressure increases. The expression "pressure compensating" as used herein does not necessarily mean that the flow rate through the valve will be totally immune to inlet pressure fluctuations.
My copending application Ser. No. 603,142 filed on Aug. 8, 1975 and entitled "Drip Irrigation Valve With Helical Flow Path" discloses a drip irrigation valve which, in addition to providing flow rate adjustability and pressure compensation, has an advantageous self-cleaning feature. This latter valve utilizes axially movable components at least one of which is relatively difficult to mold.